The invention relates to a Bulbine frutescens extract, a method of manufacturing same, use of same in the medical and cosmetic fields and compositions comprising the inventive extract.
Bulbine frutescens (L.), which belongs to the family of Asphodelaceae/Liliaceae, is also known by the terms “Rankkopieva”, “Ibhucu” or “Ithethe elimpofu”. The German name is “stalked bulbine.” This plant is widespread in South Africa, where more than 40 subspecies are known. It grows preferentially in sandy soil. The plant has a root stalk with numerous wiry roots; the leaves are 15 cm long and 4 to 8 mm thick, of a light green color and are fleshy and without hair. From April to August the plant bears yellow, orange or white blossoms in dense elongated flower clusters with a length of up to 30 cm and with a bearded stamen.
It is known that a gelatinous fluid obtained by expressing the leaves is used as an all-purpose curative against burns, abrasion wounds, damaged skin, skin rashes, eczema and ringworms, for example. The juice is expressed from a freshly picked leaf and applied to the area of skin affected. A tea infusion prepared from the fresh leaves is also known and is alleged to be helpful against colds, coughs, arthritis, diarrhea, bladder infections, infections of the urinary tract and some sexually transmissible diseases. However, the efficacy of this preparation has not yet been proven clinically nor have any professional reports about this been published.
Regarding the chemical composition of the fluid expressed from the leaves of plants in the Bulbine genus, however, some information is available. For example, Van Staden (Phytochemistry 35, 685 (1994)) has reported that knipholone is present in Bulbine latifolia and Bulbine frutescens. Knipholone is derived from 1,8 dihydroxyanthraquinone; it has a methyl group in position 3 and a 2,6 dihydroxy 4 methoxy 3 acetylphenyl group in position 4, also known as 2 acetyl-phloroglucine methyl ether group. Isoknipholone has the 2-acetylphloroglucine methyl ether group in position 9. 1,8 Dihydroxy 3 methylanthraquinone is better known as chrysophanol.
The occurrence of knipholone and its derivatives is limited practically to the Bulbine species although anthraquinones occur widely in nature. Knipholone also has been found in Kniphofia species, such as those described by Dagne and Steglich (Phytochemistry 23, 1729 (1984) and Bull. Chem. Soc. Ethlop. 32 1 (1987)). Leistner et al. (Chem. Pharm. Bull. 52, 1262 (2004)) have described knipholone derivatives in Kniphofia foliosa and Kniphofla tuckii, which are native to Ethiopia, with an emphasis on the glucose and disaccharide gentiobiose as the glucosidic part of these water-soluble anthraquinones.
Since the first report about knipholone in representatives of the Asphodelaceae family, a number of other aryl-substituted chrysophanol derivatives have been described either as glycosides or aglycones. Bringmann et al. (J. Nat. Prod. 65, 1117 (2002)) have described gaboroquinone A and B, 4′-O-demethylknipholone-4′-O-β-d-glucopyranoie and phenyl anthraquinones from the roots of Bulbine frutescens. Some of these compounds have exhibited moderate to good antiplasmoidal and antitrypanosomal effects in vitro. Bringmann et al. (2007) also found dimeric knipholone derivatives (joziknipholone A and B) in the roots of Bulbine frutescens. These joziknipholones have exhibited an effect in vitro against the chloroquine-resistant strain K1 of the malaria pathogen Plasmodium falciparum and a moderate effect against L5178Y leukemia lymphoma mouse cells.
Rabe and Van Staden (J. Ethnopharmacology 56, 81 (1997)) have investigated the in vitro effect of dried extracts from the leaves of Bulbine frutescens for their microbiological effect against Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis. However, these extracts have proven to be ineffective. Van Staden and Drewes tested knipholone in vitro for its antimicrobial effect against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Micrococcus luteus and Candida albicans, but these also proved ineffective. No reports about the bioavailability of Bulbine frutescens have been published.
Substituted 1,8-dihydroxyanthraquinones have also been found in various species of aloe such as Aloe barbadensis, Aloe ferox (which also belong to the Asphodelaceae family) and species of rhubarb such as Rheum rhabarbarum and Rheum palmatum (Chinese rhubarb). The anthraquinones in the aloe and rhubarb species lack the 2 acetylphloroglucine methyl ether group which is present in knipholone. The methyl group in position 3 may also be present in an oxidized form, either as the hydroxymethyl group, as an aldehyde or as an acid. The anthraquinones in aloe and rhubarb species are present as glycosides. The sugar radicals may be pentoses and/or hexoses. These are readily water soluble but after aging of these extracts or excessive heating, hydrolysis may occur and the anthraquinones become insoluble in water.
The anthraquinones present in Bulbine species have a completely different physiological potential than the anthraquinones originating from species of aloe and rhubarb. The anthraquinones from aloe and rhubarb species often have laxative properties. In 1987, the fundamental compound 1,8 dihydroxyanthraquinone (Danthron®) was taken off the market throughout the world because of the well-founded suspicion that this compound is carcinogenic for humans. However, toxic adverse effects such as those with aloe/rhubarb anthraquinones essentially do not occur with knipholone anthraquinones. Therefore, the manufacturers of aloe gels make a great effort to reduce the anthraquinones component as much as possible because it is mainly the polysaccharide component that is important in aloe gels.
There is thus a demand for supplying additional means for various therapeutic purposes and other means which have an improved and verifiable spectrum of effects in comparison with known compounds, that can be used in various fields and are easily obtainable and applicable. While a variety of compositions and methods have been made and used, it is believed that no one prior to the inventor has made or used an invention as described herein.